Obesity has become increasingly prevalent over the years and is one of the most common health risk factors in pregnancy. Latest figures for England show around 22% of pregnant women are obese, 28% are overweight and 47% within a normal range.
Obesity can increase the risk of complications for both mother and baby, but these can be minimised with the care and support outlined in the new guidance. This includes recommendations on how to manage weight before, during and after pregnancy to improve health outcomes for mothers and babies.
Complications for women who are obese include higher risk of miscarriage, stillbirth, pre-eclampsia, gestational diabetes and postpartum haemorrhage – the most common cause of maternal death directly related to pregnancy in the UK. For example:
- The overall likelihood of a miscarriage in early pregnancy is 1 in 5 (20%). If you have a Body Mass Index (BMI) of 30 or above, your risk increases to 1 in 4 (25%).
- The overall likelihood of stillbirth in the UK is 1 in every 200 births. If you have a BMI of 30 or above, this risk increases to 1 in every 100 births.
Babies whose mothers are obese also have an increased risk of congenital anomalies, being born pre-term, being a large baby and becoming obese and diabetic in later life.
Key recommendations include that women who are obese – with a BMI of 30 and above – should lose weight before becoming pregnant and between pregnancies.
Women should be weighed and offered advice on weight and lifestyle in primary care, such as during pre-conception counselling and appointments about contraception, the guideline suggests. A structured weight-loss programme and a referral to a dietician or an appropriately trained healthcare professional may be recommended.
Although pre-conception advice and support in primary care services is preferred, around one third of births in the UK are unplanned. For women unable to lose weight before pregnancy, the guidance recommends comprehensive, sensitive and appropriate multi-disciplinary care.
This should include a consultation to ensure women are informed about the increased risks of complications for her and her baby, and dietetic advice by a trained healthcare professional should be offered early in the pregnancy, based on guidelines from the National Institute for Health and Care Excellence (NICE).
Professor Fiona Denison, Chair of Translational Obstetrics at the University of Edinburgh and lead author of the RCOG’S guideline, said:
“A woman and her partner’s diet and lifestyle before conception significantly impact on the chances of conceiving naturally and having a healthy pregnancy and birth, as well as influencing the health of children in later life.
“Pregnancy provides an opportunity for healthcare professionals to connect with women at a time when they are generally more concerned about their health. By making healthy changes to their diet and exercise, women who are obese may limit the amount of extra weight they gain during pregnancy. Losing weight by dieting or taking weight loss drugs is not recommended as this may harm the health of the unborn baby.
“We hope these new guidelines will support healthcare professionals to provide women with sensitive and comprehensive advice, based on the best available evidence, and to ultimately empower them to maintain a healthy weight and lifestyle before, during and after pregnancy.”
The guidelines state that although being obese is itself not a reason to be admitted to a consultant-led unit, women who are obese are more likely to require an induction of labour, emergency caesarean birth or a vaginal birth that requires a medical intervention.
The additional care that can be provided promptly in a consultant-led unit should she need it must be discussed with each woman so that she can make an informed choice about her planned place of birth. This requires a multi-disciplinary, individualised approach, and may need to involve consultations with an obstetrician, anaesthetist, and midwife. Women who are obese may also experience difficulty in breastfeeding and may need additional support.
Even slight weight gain after pregnancy is associated with greater risk of problems in subsequent pregnancies, the guidance notes. It suggests women who are obese should be offered referral to weight management services after giving birth to help them achieve a healthy weight before embarking on a future pregnancy.
Dr Daghni Rajasingam, Consultant Obstetrician and spokesperson for the RCOG, said:
“Pregnant women who are overweight or obese have increasingly more complex health needs. It is crucial that healthcare services – from primary care to maternity services – offer specialist weight management advice and support for women who are planning a pregnancy and for those women who are pregnant who are planning a pregnancy and for those women who are pregnant. We must ensure maternity services must be well-resourced to manage any pregnancy and birth complications that may arise to ensure the safest possible pregnancy and a healthy baby.”
Kate Brian, Chair of the RCOG’s Women’s Network, said:
“Maternal obesity does increase the risk of complications for a woman and her baby, but this new guideline will help healthcare professionals and women to reduce their risk. We hope the new guidance and accompanying information for women about being overweight in pregnancy and after birth will empower women to engage with the advice and support available to them.”
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Other recommendations from the latest guidance include:
- Fetal size, presentation and monitoring of fetal heart tracing may be more challenging during pregnancy and more scans may be required.
- Gestational diabetes must be screened for early in pregnancy and medication provided if required.
- Blood pressure and risk of blood clots should be monitored during and after pregnancy and medication provided if required.
- Women with more than one risk factor (BMI of 35 or greater, first pregnancy, maternal age of more than 40 years, family history of pre-eclampsia and multiple pregnancy) may benefit from taking 150mg aspirin daily from 12 weeks of gestation until the birth of the baby to reduce risk of developing blood pressure problems.
- For women who have not previously exercised routinely, 15 minutes of continuous exercise, three times per week, increasing gradually to 30 minute sessions every day, is recommended. Examples of suitable exercises include swimming, walking and pregnancy yoga.
- Presently there is no evidence-based UK guidance for optimal weight gain or loss during pregnancy but women are encouraged to maintain a healthy weight before, during and after pregnancy by eating a well-balanced diet and taking part in regular exercise.
The RCOG co-developed a new digital tool, Planning for Pregnancy, which provides tailored information for women on how they can prepare before conception in order to have a healthy pregnancy.
The RCOG worked with the National Charity Partnership to bust the myth that women need to ‘eat for two’ during their pregnancy and make it easier for women to understand how to make healthy choices during pregnancy to avoid unhealthy weight gain.
The Lancet published a three-part series on pre-conception health earlier this year. It found that the weight, diet and health of both parents before conception can have profound implications on the pregnancy and health of their children.
The following resources are available to women and their families to help them maintain a healthy weight:
Please cite the guidance as follows:
Denison FC, Aedla NR, Keag O, Hor K, Reynolds RM, Milne A, Diamond A, on behalf of the Royal College of Obstetricians and Gynaecologists. Care of Women with Obesity in Pregnancy. Green-top Guideline No. 72. BJOG 2018; https://doi.org/10.1111/1471-05386.000:1-45.
The RCOG’s first Green-top Guideline on management of obesity during pregnancy is a revised edition of the 2010 joint RCOG guidance with the Centre of Maternal and Child Enquiries.